Electromagnetic radiation is employed for many types of wireless data communication, which can include radio frequency (RF), microwave, infrared, and visible spectral bands. This present disclosure can describe new methods and techniques of spectroscopically probing various media and optimizing wireless electromagnetic communication, particularly wireless communication in underwater environments.
When an electromagnetic beam encounters a material, it can interact with it in several different ways. These interactions can depend on the wavelength of the electromagnetic wave and the nature of the material. One particular case can be presented, that of visible light propagation. Photons (electromagnetic radiation) can interact with a medium in some combination of reflection, absorption and transmission. Some materials, such as glass or purified water, transmit much of the light incident upon them and reflect very little of it; such materials are called optically transparent. Many other solids and liquids are also highly transparent. Another factor affecting the optical properties of materials is scattering. In this process, photon energy remains largely unchanged but the trajectory is redirected along another path, and the detector no longer observes this radiation. The process of absorption occurs when photon energy is converted into another form (e.g., heat), and the photons are no longer observable by the system.
In the prior art, there can exist numerous products to analyze attenuation. In the specific case of visible radiation in a seawater medium, the ac-s In-Situ Spectrophotometer manufactured by WET LABS® can use a lamp source and a detector separated by a fixed, permanent distance. The Eco BB9 scattering meter made by WET LABS® is compact, and it can use multiple LED sources to characterize the water, but it only measures backscattering alone at one fixed angle to deduce particle concentration. These devices are not known to be capable of lock-in techniques that enable sensitive detection, nor do they permit high-speed communication.
Non-self-contained, two-sided optical communication links in the prior art do not typically contain retro-reflectors. Instead, such systems usually have a transmitter at one end and a receiver at the other end. In other prior art systems, light that is backscattered from turbid seawater can be extinguished by using crossed polarizing optical elements, but the prior art systems of this type can only use one laser, and cannot adapt to changing environments. Additionally, the light is directed through a small hole in a metal mirror, and return light reflects from the same mirror. A major drawback of this mirror-hole method is that some desired light may leak back through the initial hole, reducing the accuracy of the measurement.
In view of the above, it can be an object of the present invention to provide a wavelength optimization system and methods for underwater optical communication that can analyze underwater conditions to determine an optimum wavelength for optical communications. Another object of the present invention can be to provide a wavelength optimization system for underwater optical communication that can continuously monitor attenuation losses due to absorption and scattering in the environment. Still another object of the present invention can be to provide a wavelength optimization system for underwater optical communication that can switch communication wavelengths if changing environmental conditions warrant doing so. Yet another object of the present invention can be to provide a wavelength optimization system for underwater optical communication that can be relatively easy to manufacture and use in a cost-effective manner.